Fig. 6

Changes in transmission in pre- and post-vaccination scenarios? Figure shows the proportion of disease-free weeks (fade-outs) for various population sizes from the stochastic formulation of the model. Panel a compares the symptomatic cases in the aP vaccination era with those in the pre-vaccine era; panel b compares the symptomatic to asymptomatic cases in the vaccine era; panel c compares the asymptomatic cases in the post-vaccine era with those in the pre-vaccine era. These results demonstrate no changes in transmission due to vaccination. Parameters: birth rate (μ) = death rate (ν) = 1/75 years −1; recovery rates for symptomatic (γs) and asymptomatic (γa) = 14 days −1; probability of symptomatic infection (σ) = 0.25; transmissibility (β) is calculated per value of R0